Such cassettes are designed to receive and to protect surplus lengths of optical fiber that are left at the end of one or more optical cables, and optionally to receive and to protect connections or "splices" between the fibers of a plurality of cables or between such fibers and optical jumpers.
Document FR-A-2 601 785 describes such a cassette for optical fibers. The cassette is assigned to coiling and to protecting surplus lengths of fiber at the end of a cable. That cassette includes a bottom in which a recess is delimited between a central cylinder on the bottom and a peripheral rim. Two access channels in the rim open out into the recess. The surplus lengths of fiber are coiled around the cylinder. A ring is preferably placed around the cylinder for the purposes of coiling the fibers. The ring is removed once all the fibers have been coiled, so as to give them more freedom, between the cylinder and the peripheral rim. A cover closes the cassette and covers both of the access channels.
In that document, the optical fibers extracted from the cable are protected inside individual flexible tubes when they are held in place in the access channels of the cassette, whereas they are bare when they are coiled inside the cassette.
The access channels are rectangular in cross-section or semi-circular in cross-section depending on whether the cable from which the fibers are extracted has a flat structure or a grooved-rod structure. The tubed fibers are aligned side-by-side in the rectangular section channel and are held thus by the cover fixed to the cassette. The tubed fibers are installed in the grooves of a barrel which is grooved lengthwise, and which is mounted in the semi-circular section channel, and the fibers are retained by the cover holding the barrel stationary, the cover then in turn being provided with a semi-cylindrical channel receiving the barrel.
Those ways of holding the fibers in the access channels correspond to two specific embodiments of cassettes for the two types of cable with which they are used. Those holding means require the fibers to be tubed even though they are coiled bare. The fact that the tubed fibers are aligned side-by-side inside the rectangular section access channel does not enable the fibers to be properly separated and properly held. With the variant embodiment, in which a barrel is placed in each semi-circular section access channel, it is difficult to install the fibers and to hold them in place temporarily until the cover has been fixed on the cassette. Furthermore, the tubed fibers being distributed around the periphery of a barrel makes it difficult for the fibers to be coiled loosely around the cylinder over the height of the recess surrounding the cylinder.
Document EP-A-0 216 073 discloses a cassette having two access channels provided between the ends of one of the two large edges of the cassette and the facing ends of the two small edges of the cassette. Each access channel receives a clamping body for clamping fibers and having parallel grooves, which clamping body is installed with its grooves in either one of two possible directions. To this end, the clamping body carries a projection projecting from underneath its bottom, which projection is received in one of two perpendicular slots that are provided on the cassette.